Dear All,
As my own research activity is moving towards auditory scene analysis, I
thought this question very timely. I broke out the problem into two
parts, one being at the cochlear level and the other, attention. At the
cochlear level, one has to assume that source separation takes place all
the time, probably using the criteria of differing F0's for this
segregation. Hence, attention is the process of picking a particular
source, and here is where the difficulties arise. There could be many
factors that could cause a shift in our attention, including an
involuntary one if one of the lions was closer to us than the other.
From a research viewpoint, I would assume that the first step would be
to determine how the cochlear segregates the sources, where the
determination of F0's becomes highly critical. My own approach has been
documented at my website, www.tonepitch.com and uses a new approach to
frequency analysis. The extension of the method towards source
segregation requires that I pick not only the most active F0, but a few
more in equal or decreasing importance. Assuming that this works, and it
should if the source F0's are reasonably well separated, one could then
proceed to check what the criteria are that causes involuntary switches
in attention. I am sure that a sudden increase in loudness will play an
important part.
I hope this helps rather than confuse the problem. Cheers,
Randy Randhawa

Dear all,

I have a question of general interest about auditory scene analysis, and
would be grateful for any views on the subject.

Humans have the remarkable ability to interpret multiple events and
perceive distinct sources within a complex sound environment. The
concept of perceptual streams of information is explained in (Bregman
A.S., Auditory Scene Analysis: The Perceptual Organization of Sound, MIT
Press, 1990). My question is: are we really capable of perceptually
segregating multiple sources concurrently, or are we just focusing our
attention on one source, and then shifting it very quickly to another
source? Evolutionarily speaking, I can see it would be advantageous if
we were being chased by two lions rather than one, to be able to
concentrate on both simultaneously. However, I also have the impression
that if lion 1 roars, we will forget about lion 2 for a moment, and vice
versa. If both roar at the same time, are we now listening to two
separate lions or just a general sound of lions roaring?
In any case, run for it...